The present application relates to manipulating the thickening time and set time of settable compositions during wellbore operations.
Settable compositions like cements and hardenable resin systems may be used in a variety of subterranean applications. For example, when constructing a well, a pipe string (e.g., casing, liners, expandable tubulars, etc.) may be run into a wellbore, and the settable composition is placed in an annular space between the exterior surface of the pipe string and the wellbore. This forms an annular sheath or hardened mass that may support and position the pipe string in the wellbore and bond the exterior surface of the pipe string to the subterranean formation. Among other things, the annular sheath surrounding the pipe string functions to prevent the migration of fluids in the annulus, as well as protecting the pipe string from corrosion. Settable compositions may also be used in remedial methods, for example, to seal cracks or holes in pipe strings or annular sheaths, to seal highly permeable formation zones or fractures, to place a plug, and the like.
Settable compositions often include set time modifiers (e.g., set accelerators and set retarders) that alter the thickening time and set time of the settable composition so that the settable composition can be pumped into place before becoming too thick to pump or setting. Proper setting time of the settable compositions reduces the time and cost associated with wellbore operations. For example, wellbore operations are generally ceased while the settable composition hardens. So, if the settable composition is over-retarded, the set time may be excessive, which is expensive, non-productive time. Further, because the settable composition has not hardened, fluids may infiltrate the settable composition and further delay hardening or reduce the final strength of the hardened mass. In another example, if too much set accelerator is used, the settable composition may harden before it has reached the desired location. Then, expensive wellbore operations to drill out the improperly placed harden mass need to be performed.